C / C++ / MFC

25-Oct-07 0:29

Hello,
I have a question about callback function.
My code is waveInOpen(&hWav,0, &wfx,WaveInCallback ,0, CALLBACK_FUNCTION);
But it comes some problems, the error message is

error C3867: 'p2p::Form1::WaveInCallback': function call missing argument list; use '&p2p::Form1::WaveInCallback' to create a pointer to member

I dont realize what happened.
Can anybody solve this question for me?

Jane

Nishad S25-Oct-07 0:36

25-Oct-07 0:36

This error happens when you tried to take the address of a member function without qualifying the member function with its class name and the address-of operator.

Can you show the callback function declaration?

- NS -

minihotto25-Oct-07 0:40

25-Oct-07 0:40

OK.
void CALLBACK WaveInCallback(HWAVEIN hw, UINT uMsg,
DWORD_PTR dwInstance, DWORD_PTR dwParam1, DWORD dwParam2)
{
waveInAddBuffer(hw, (WAVEHDR*)dwParam1, sizeof(WAVEHDR));
}
I create it in the From.h.
But I don't know where to allocate it.

Nishad S25-Oct-07 0:49

25-Oct-07 0:49

Isn't it a static function? AFAIK it should be static function.

Also I found a mismatch with the documentation in MSDN. See...
void CALLBACK waveInProc(
HWAVEIN hwi,
UINT uMsg,
DWORD dwInstance,
DWORD dwParam1,
DWORD dwParam2
);
You are using DWORD_PTR instead of DWORD. But I am not sure about this Frown | :(

- NS -

minihotto25-Oct-07 0:56

25-Oct-07 0:56

Appreciate for ur reply.
But it's still same.

Nishad S25-Oct-07 1:01

25-Oct-07 1:01

Try to cast like
waveInOpen(&hWav,0, &wfx,(DWORD_PTR)WaveInCallback ,0, CALLBACK_FUNCTION);

- NS -

minihotto25-Oct-07 1:18

25-Oct-07 1:18

It comes other errors.@@
1.error C3374: can't take address of 'p2p::Form1::WaveInCallback' unless creating delegate instance
2.error C2440: 'type cast' : cannot convert from 'void (__clrcall p2p::Form1::* )(HWAVEIN,UINT,DWORD_PTR,DWORD_PTR,DWORD)' to 'DWORD_PTR'

Nishad S25-Oct-07 1:26

25-Oct-07 1:26

Please show me the declaration of the callback function. Not in the cpp but inside the class in header file.

- NS -

David Crow25-Oct-07 2:58

David Crow

25-Oct-07 2:58

NS17 wrote:
Please show me the declaration of the callback function.

It's declared in mmsystem.h:

void CALLBACK waveInProc(
  HWAVEIN hwi,       
  UINT uMsg,         
  DWORD dwInstance,  
  DWORD dwParam1,    
  DWORD dwParam2     
);

Nishad S25-Oct-07 17:09

25-Oct-07 17:09

DavidCrow wrote:
It's declared in mmsystem.h:

I meant how he declared the the function to use as callback.

- NS -

minihotto25-Oct-07 3:13

You're riding the wrong train, it seems.

25-Oct-07 3:13

public ref class Form1 : public System::Windows::Forms::Form
{
public:
Form1(void)
{
InitializeComponent();
//
//TODO: Add the constructor code here
//
}
int call_id;
void CALLBACK WaveInCallback(HWAVEIN hw, UINT uMsg,DWORD_PTR dwInstance, DWORD_PTR dwParam1, DWORD dwParam2)
{
WAVEHDR* curhdr = (WAVEHDR*)dwParam1;
waveInAddBuffer(hw, curhdr, sizeof(WAVEHDR));
}

............

I put in the class form1

jhwurmbach25-Oct-07 4:53

jhwurmbach

25-Oct-07 4:53

minihotto wrote:
public ref class Form1 : public System::Windows::Forms::Form

You very certainly wanted to ask that in the "Managed C++"-Forum?!?
Sniff | :^)

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Re: You're riding the wrong train, it seems.

Hamid_RT25-Oct-07 5:14

Hamid_RT

25-Oct-07 5:14

I agree ask on the correct forum.

Nishad S25-Oct-07 17:08